MAGNOLIAEVENT
OPERATION HARDTACK
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The MAGNOLIA device was detonated at O600M, 27 May 1958, 3,000
faat southusst of the center of Yvonne Island.
The cloud rose immediately
to 44,000 feet and stabilized at 41,000 feet with the base at 15,000 fect.
Radar confirmed this ncsition, and the initial cloud movement was westerly.
The middle segment remained over ground zero, and the upper and lover
levala moved on a bea-ing of 250 degrees.
2.
The P2V aircraft was vectored from Alvin to Keith at 0633M, and
it reported reaqings of Zero at 500 feet.
The northern chain was then
surveyed, with the highest reading recoried ovar Alice:
5 mr/hr, at OS47M,
Tne lagoon srea was svapt in 10edegres increments, and in the center of the
lageon at 500 fost, 7 r was recorded at 0735M,
Tha aircraft was considered
contaminated and was instructed to wash down at Fred.
Reentry was declared
at 0730M,
3.
A helicopter ground survey was initiated at 0745M.
The highsat
reqding wes racorded at Alice, with 22,000 mr/hr, which 1s attributed to
the YELLOWWCOD event.
Other islands in tha northern chain rangsd ffom
2 ne/hr to 120 mr/hr, with Yvonne reading 1,200 to 2,000 mr/hr.
4.0
A second helicopter survey wae nade at 1430M.
The southern chain
=
indicated only background with tha exception of Leroy, which r2ed 35,000 mr/rh
at twenty-five feet,
This high reading is attributed to a amall section of
the cloud which did not move out of the legcon as anticipated.
reading accounted for the contamination of the P2V, BEST COPS
TAB A
This high
‘04 iLABLE
J 21